Wastegate position sensor for wastegate and engine pressure sensor diagnostics

Abstract

An engine pressure sensor monitoring system uses the position of a wastegate in a turbo-charged engine when known and calibrated engine operating conditions occur to provide diagnostic information for various engine pressure sensors and for the operation of the wastegate itself. Discrete measurement windows are defined for engine conditions with specific values for parameters that may include rpm, torque, injection timing and fuel consumption. Other sensor readings for intake manifold pressure, turbocharger compressor output pressure, peak cylinder pressure, and wastegate valve position during these measurement windows should match predicted values. If measured and predicted values do not match, one or more sensors may be bad and an alarm may be raised.

What is claimed is: 
     
       1. A method of performing sensor diagnostics in an engine, the method comprising:
 defining a measurement window for performing sensor diagnostics, the measurement window occurring when a plurality of engine conditions fall within respective value ranges; 
 identifying the measurement window during operation of the engine; 
 collecting wastegate position data and sensor data within the measurement window; and 
 performing a diagnostic test using the sensor data collected within the measurement window, the diagnostic test including:
 determining a predicted output value for a first sensor as a function of wastegate position; and 
 comparing an actual value of the first sensor taken during the measurement window and the predicted output value; and 
 when the predicted output value and the actual value fail to meet a matching criterion, setting an alert indicating a probably failure in the first sensor. 
 
 
     
     
       2. The method of  claim 1 , wherein performing the diagnostic test further comprises:
 within the measurement window, collecting additional output values for each of a plurality of sensors; 
 determining additional predicted values for each of the plurality of sensors, each of the additional predicted values being a function of the wastegate position; 
 comparing the additional output values for each of the plurality of sensors to the corresponding additional predicted values for each of the plurality of sensors; 
 when a number of sensors that fail to meet their respective matching criteria exceeds a threshold value, setting a wastegate alert indicating a problem with the wastegate. 
 
     
     
       3. The method of  claim 2 , further comprising:
 when the number of sensors that fail to meet their respective matching criteria is less than or equal to the threshold value, setting a respective additional alert for each of the plurality of sensors that fails to meet its respective matching criterion. 
 
     
     
       4. The method of  claim 2 , further comprising:
 collecting non-window wastegate position data and non-window sensor data taken outside the measurement window; 
 determining predicted non-window values for each of the plurality of sensors, each of the predicted non-window values being a function of the wastegate position; 
 comparing the measured non-window output value for each of the plurality of sensors to the predicted non-window values for the corresponding each of the plurality of sensors; and 
 when a number of sensors that fail to meet their respective matching criteria exceeds a second threshold value, setting the alert indicating a problem with the wastegate. 
 
     
     
       5. The method of  claim 1 , wherein defining the measurement window for performing sensor diagnostics comprises:
 defining a respective value range for each of a plurality of engine operating parameters, the engine operating parameters including one or more of engine rpm, engine fuel consumption and engine fuel valve opening timing. 
 
     
     
       6. The method of  claim 1 , wherein defining the measurement window comprises requiring the measurement window occurs during steady state operation of the engine. 
     
     
       7. The method of  claim 1 , wherein defining the measurement window comprises selecting values for a combination of engine performance characteristics including engine operating parameters and engine input data developed at an engine controller coupled to the engine. 
     
     
       8. The method of  claim 7 , wherein the engine operating parameters include one or more of engine speed, throttle condition, and engine load and wherein the engine input data includes one or more of injection shot mode, injection timing, fuel pressure, and fuel quantity. 
     
     
       9. The method of  claim 1 , further comprising:
 monitoring over a predetermined time a relationship of intake manifold pressure vs. wastegate position; and 
 setting a wastegate alarm when a value of intake manifold pressure vs. wastegate position changes beyond a predetermined limit. 
 
     
     
       10. The method of  claim 1 , wherein collecting wastegate position data comprises using a Hall-effect sensor to report a position of a shaft coupled to a low-pressure side of a wastegate valve. 
     
     
       11. The method of  claim 1 , wherein the measurement window occurs when a different plurality of engine parameters and engine operating data fall within respective predefined ranges. 
     
     
       12. The method of  claim 1 , wherein the first sensor is one of a intake manifold air pressure (IMAP) sensor, a turbocharger compressor-out pressure sensor, and a turbocharger input pressure. 
     
     
       13. The method of  claim 1 , wherein determining a predicted output value of the first sensor includes solving an algorithm that includes wastegate position, one or more engine operating data, and one or more engine parameters each multiplied by respective constant values determined empirically during engine calibration. 
     
     
       14. A system for performing a sensor diagnostic test in an engine comprising:
 a wastegate having a wastegate position sensor that reports a displacement of the wastegate; 
 a sensor being evaluated by the sensor diagnostic test, the sensor configured to report a value of an engine parameter; 
 an engine controller coupled to the engine, the sensor, and the wastegate position sensor, the engine controller executing stored instructions that cause the engine controller to perform the sensor diagnostic test including:
 analyzing at least the displacement of the wastegate to determine a predicted output value of the sensor; and 
 setting an alert indicating a failure in the sensor when the predicted output value of the sensor is outside a predetermined range of the value reported by the sensor. 
 
 
     
     
       15. The system of  claim 14 , further comprising:
 a plurality of additional sensors coupled to the engine controller that each report respective values of additional engine parameters; and 
 engine operating data developed at the engine controller, wherein analyzing at least the displacement of the wastegate to determine a predicted output value of the sensor further includes analyzing the engine operating data and the additional engine parameters to determine the predicted value of the sensor. 
 
     
     
       16. The system of  claim 15 , wherein the engine controller executes additional stored instructions for:
 determining a predicted output value a plurality of additional sensors; 
 comparing the predicted output value of the plurality of additional sensors to corresponding values provided by the respective plurality of additional sensors; 
 when less than or equal to a threshold number of the plurality of additional sensors fail the comparison, setting individual alerts for each sensor that fails the comparison; 
 when more than the threshold number of the plurality of sensors fail the comparison, setting a wastegate alert indicating a potential failure of the wastegate. 
 
     
     
       17. The system of  claim 15 , wherein the engine controller executes additional stored instructions including:
 monitoring the engine parameters and the engine operating data to determine a measurement window that matches select engine parameters and select engine operating data corresponding to engine calibration test points; and 
 performing the sensor diagnostic test during the measurement window. 
 
     
     
       18. A method of performing a sensor diagnostic test for an engine, the method comprising:
 collecting data from a plurality of sensors including a wastegate position sensor that reports a position of a wastegate; 
 determining a measurement window by analyzing the collected data; and 
 analyzing the collected data read during the measurement window to develop a predicted value of a first sensor based at least in part on the wastegate position; and 
 setting an alert for a failure of the first sensor when the predicted value of the first sensor and an actual value reported by the first sensor fail to meet a matching criterion. 
 
     
     
       19. The method of  claim 18 , further comprising:
 analyzing the collected data read during the measurement window to predict values of two or more additional sensors of the plurality of sensors; and 
 when a number of two or more additional sensors that fail to match predicted values and actual reported values is below a threshold number, setting additional alerts for a failure of each sensor that fails the match. 
 
     
     
       20. The method of  claim 19 , further comprising:
 when a number of the two or more additional sensors that fail to match predicted values and actual reported values is equal to or greater than the threshold number, setting a wastegate alert for a failure of the wastegate.